how can I add an Application on Launchpad?

What you can do is to open System Information (in /Applications/Utilities) and choosing Applications in the sidebar. Then, look for the apps you want to add to Launchpad and go to the folders where they are. Finally, drag their icons to the Launchpad icon on the Dock.

Network Utility has been moved to /System/Library/CoreServices (or /System/Library/CoreServices/Applications). Go to this folder and drag its icon to the Launchpad

You are welcome

Hi Mende1

I tried this but looks like the launchpad icon is locked as it won't work when I put the icon on top of launchpad

can you help

Thanks

Craig

If by "locked" you mean that the icon doesn't highlight when you're ready to drop a new app onto it, I have the answer to that:

You have to drag the new app directly onto the Launchpad dock icon without ever touching the dock on either side of it (which would make a space open up as though you would add the app to the Dock). If you see that space open up, the Launchpad icon will not accept any drops. Drag away from the dock and try again.

(Even so, certain apps just won't get added to Launchpad no matter what I try. Still flaky even in Mavericks.)